In recent years, as a display unit of various electronic devices including mobile phones and hand-held gaming machines, a liquid crystal display with a touch panel which also has a function of an input device is widely used.
The touch panel has a touch panel substrate in which optically-transparent conductive layers or the like are laminated on a transparent substrate and in which a stack of films are formed on the outmost surface side thereof. The touch panel substrate detects an operation position of a finger or the like by a change in capacitance or the like.
Based on the structures and detection systems, touch panels are categorized into various types such as a resistance film type touch panels and a capacitance type touch panels.
For example, a touch panel substrate that is provided with an upper substrate and a lower substrate which are film-shaped and have optical transparency is known. On the top surface of the upper substrate, a plurality of substantially band-shaped upper conductive layers made of a material with optical transparency such as indium tin oxide are formed so as to be arranged in the front-rear direction. Furthermore, on the layers of the indium tin oxide or the like, a plurality of upper electrodes in which conductive metal foil such as copper or silver are stacked by vapor deposition or the like are formed in the left-right direction, which is a direction orthogonal to that of the upper conductive layers. On the top surface of the lower substrate, a plurality of substantially band-shaped lower conductive layers made of a material with optical transparency such as indium tin oxide are formed so as to be arranged in the left-right direction, which is a direction orthogonal to that of the upper conductive layers. Furthermore, a plurality of lower electrodes, which are similar to the upper electrodes and first ends of which are coupled to edges of the lower conductive layers, are formed in the left-right direction parallel with that of the lower conductive layers.
In addition, to the touch panel substrate, a film-shaped cover substrate with optical transparency is attached with an adhesive so as to overlap the top surface of the upper substrate.
FIG. 5 is a cross-sectional view of a conventional touch panel. In FIG. 5, reference symbol P denotes a touch panel substrate, and reference symbol C denotes a cover substrate. On a surface of the cover substrate C which faces the touch panel substrate P, there is provided a light shielding film th with optical opacity in an edge region E positioned along an outer circumference of or outside of a touch area (display area) T on which touch operation is performed.
It is known that the light shielding film th is formed so as to have a thickness of approximately 5 μm to 20 μm on the cover substrate C by printing or the like, as shown in Patent Document 1.